TGF-β1is a glycoprotein belonging to a superfamily of structurally related regulatory proteins (cytokines) included within one of the three isoforms described in mammals (TGF-β1, 2 and 3). The most abundant isoform is TGF-β1, which consists of a 25 kDa homodimer composed of two subunits joined by a disulfide bond. The amino acid sequence of human TGF-β1 has been described by authors such as Derynck K et al., “Human transforming growth factor-beta complementary DNA sequence and expression in normal and transformed cells”. Nature 316 (6030), 701-705 (1985).
TGF-β1is a molecule with a highly preserved sequence in evolutive terms. Although it was originally defined by its capacity to induce adhesion independent of proliferation and morphological changes in rat fibroblasts, subsequent investigations have shown that TGF-β1 is a general inhibitor of proliferation of a broad range of cell types. The molecule is produced by a great variety of cell types and in different tissues during all phases of cell differentiation. It has a large series of biological effects, with the generation of potent and very often opposite effects in relation to development, physiology and immune response. Information on the role of TGF-β1 in liver regeneration and differentiation, and in liver fibrosis, as well as on the effects of the molecule upon the extracellular matrix, can be found in Spanish patent application ES 2146552 A1.
With the purpose of exploring the mechanism of action of TGF-β1, some ten proteins (membrane receptors and extracellular matrix proteins) have been reported to interact with this cytokine.
On the other hand, since many diseases or pathological alterations are associated with excessive or deregulated expression of TGF-β1, e.g., fibrosis associated to organ or tissue function loss, or surgical or esthetic complications, it is of interest to search for products capable of inhibiting the biological activity of TGF-β1—since such products can be potentially used in human or animal therapy to block the pathological consequences of excessive or deregulated TGF-β1 expression.
Several strategies have been used to inhibit the biological activity of TGF-β1 including the use of: (i) specific neutralizing antibodies; (ii) antisense oligonucleotides sequences of the gene encoding TGF-β1 which block its expression; or (iii) soluble receptors for TGF-β1 that act in a way similar to antibodies. The use of antibodies affords total and specific blockage of this cytokine (TGF-β1), though certain side effects are enhanced by both the presence of exogenous immunoglobulins in blood and the effects derived from the systemic blockage of TGF-β1. In addition, immunoglobulin stability over time does not allow short-time control of the blocking activity of this cytokine. Antisense oligonucleotides sequences inhibit TGF-β1 production at gene expression level—a fact that can generate important deregulation of all processes in which this cytokine participates.
Another strategy has recently been developed, based on the use of peptides that inhibit the biological activity of TGF-β1. In this sense, Spanish patent application ES 2146552 A1 describes some synthetic peptides originating from both TGF-β1 and its receptors, or from proteins capable of binding to TGF-β1, and which can be used as inhibitors of the biological activity of TGF-β1.